In flooring applications, it is known to pour hardenable cementicious materials such as gypsum concrete, Portland concrete containing lightweight aggregate, and the like over a subfloor or other flooring material to harden or cure in situ after being poured.
It is known, for example, that the transmission through floors of noise, such as low frequency noise from impacts, can be diminished in plural story buildings by pouring and curing, in situ, a layer of about 1.0 inches to about 2.0 inches of a hardenable, cementicious material such as gypsum concrete or Portland concrete atop a plywood subfloor. A problem with pouring hardenable cementicious material such as gypsum concrete or Portland concrete or mortar over a subfloor is that, if no steps are taken to prevent liquid moisture from soaking into the subfloor during curing or hardening of the cementicious material, water from the hardenable material will soak downwardly into the subfloor to cause deterioration of the subfloor and may also damage other underlying structure including the ceilings of rooms located beneath the water soaked subfloor. Such moisture also may contribute to mold or other fungal material at or in the flooring, subflooring and underlying ceilings over time.
In U.S. Pat. No. 6,167,668 issued Jan. 2, 2001 to Fine et al, it is proposed that a thinner layer of cementicious material can be poured over a subfloor or other flooring material to harden or set in situ if the relatively thin layer is reinforced with a fiberous mat underlaid by a flexible membrane. The mat/membrane composite serves as a crack preventative and reinforcement structure that can be stapled to the underlying subfloor. The open-space area of the mat is substantially filled with cementicious material when a layer of cementicious material is poured atop the mat. As the cementicious material hardens, cures or otherwise sets up, liquid and vapor from the cementicious material may pass through the membrane.
Floors that incorporate the mat and membrane arrangement proposed in the Fine et al patent make little, if any, use of the open-space area of the mat to vent vapor, such as water vapor, from the hardenable cementicious material during hardening or curing thereof. This lack of venting lengthens the time required to complete the hardening or curing process, and leaves the poured layer of hardenable material wetter than is desired for longer than is desired, which may delay the installation of other flooring materials atop the hardened or cured layer. The membrane of Fine et al is not a barrier that selectively permits water vapor to escape therethrough while selectively confining water in liquid form to the area atop the membrane; and, the open-space area of the mesh or mat of Fine et al is not utilized for venting vapor, but rather is employed to reinforce the layer of hardenable, cementicious material.